1. Field of the Invention
The present invention relates to a loudspeaker with a heat radiation hole suitable to be employed in a computer unit or other electronic devices which requires down-sizing or space saving, and electrical equipment employing such loudspeaker.
2. Description of the Related Art
Conventionally, as an electrical acoustic transducer (hereinafter referred to as speaker), there has been known those of the types called cone loudspeaker or, horn loudspeaker. There are various transducing principles to be employed in the loudspeakers. A cone loudspeaker as the most typical loudspeaker, is one called as dynamic direction radiation speaker. Such loudspeaker drives a cone by applying a signal current to a coil as a part of a vibration system held in a magnetic field of a permanent magnet 9 to generate an acoustic sound, as shown in a section of FIG. 3.
A frequency characteristic of the loudspeaker is variable depending upon a magnet 9, a coil 18, quality and shape of a cone 15, and supporting structure of the cone. In FIG. 3, the magnet 9 is fixed within a space defined by a yoke 10 and a yoke plate 11. The coil 18 is wound on a pole guide 19 for axial reciprocal motion relative to a pole piece 8. The cone 15 is fixed on a frame 12 at an outer periphery via a gasket 13 and an edge 14. An inner peripheral edge of the cone 15 is secured on the pole guide 19 and is elastically coupled with the frame by a damper 7. On the other hand, a cap 17 is provided at the center portion of the cone 15.
The cone loudspeaker constructed set forth above includes those having dome shaped or ribbon shaped vibration surface. In addition, there are loudspeakers applying an electrical signal between a stationary electrode and an electrically conductive film (vibration plate) stretched with a small gap from the stationary electrode for driving the film by variation of electrostatic force to cause vibration for radiating an acoustic vibration, as a static loudspeaker, electromagnetic type, piezoelectric type, ionic radiation type and so forth. These loudspeakers serve for converting electrical signal into acoustic vibration (audible sound).
In the meanwhile, in the electronic devices, such as recent personal computers or the like, a demand for a function to express information using high level image and/or sound adapting for increasing multimedia information, has been growing. Furthermore, due to grading up of information to be expressed, demanded specification for input/output performance and characteristics of video and audio information become higher progressively. Furthermore, in order to adapt for down-sizing demand of the overall system, it is required to integrally form a high performance loudspeaker with the electronic device.
However, when the conventional loudspeaker is integrally formed with the electronic device in integrating the high performance loudspeaker and the electronic device, large installation area and space becomes necessary for the speaker to make the overall device bulky. Also, in integration of the loudspeaker with the electronic device, constraints for shape and so on become quite severe to cause difficulty in obtaining desired output characteristics. Furthermore, since the casing and internal construction of the electronic device has to be optimized adapting demanded characteristics of the loudspeaker to be constraints for designing and manufacturing.